Power is fed to equipment along a transmission line in a series of independent remote power supply sections. Each power supply section comprises a power supply loop running along its entire length. The loop is constituted by the conductors of the line and loops through a power supply source. Generally speaking, the power necessary to operate the equipments situated along a power supply section is extracted by means of local power supply circuits that are inserted in series in the power supply loop at the location of each equipment.
When a power supply loop is cut, for example because of a break in cable, all the equipments in the affected power supply section cease to operate since there is a break in their power supply. Remote fault finding systems cease to operate and cannot be used to locate the break within the affected power supply section, and communication cannot be maintained up as far as the break from either end of the line. This is disadvantageous if there is a branch circuit connected to the affected portion of the line.
Preferred embodiments of the present invention avoid these drawbacks.